The present invention relates to a thermoplastic resin compositon, and more particularly to a compositon of a thermoplastic resin such as a polycarbonate or a polyester suitable for use as wrapping or packaging materials e.g. a film or a sheet, containers e.g. a bottle or engineering plastics, which has improved heat stability or improved mechnical properties.
Polycarbonates and polyesters have been practically used as wrapping or packaging materials of products requiring oxygen impermeability such as a food, or as engineering plastics such as parts of machines and tools or parts of electric machines or appliances.
The polycarbonates and polyesters have respectively characteristic and excellent properties, but there are conducted various improvements of the above thermoplastic resins in the recent requirement of technological progress to higher performance.
For instance, it is attempted to blend thermoplastic resins with various fillers, fluorocarbon resins, molybdenum sulfide, or mineral oils. However, in the attempt, the processability and the surface appearance of the molded articles are lowered and there are exhibited the coloring of the molded articles and the bleeding of additives, and moreover, in certain cases, the mechanical properties of the thermoplastic resin itself are exerted bad influence.
Also, it is attempted to blend the thermoplastic resin with a hydrolyzed ethylene-vinyl acetate copolymer for improving oxygen impermeability, adhesive strength between layers on preparation of multilayers and mechanical and electric properties. However, the composition of the thermoplastic resin and the hydrolyzed ethylene-vinyl acetate copolymer has a defect that it is difficult to improve sufficiently the mechanical strength such as the impact resistance, and for extending the use of the thermoplastic resin composition, the above defect must be solved.
The cause that the mechanical properties are lowered is considered that polyesters or polycarbonates have the poor thermal stability in the presence of a slight amount of water at high temperature on melt-molding and they are partially decomposed by impurities in a hydrolyzed ethylene-vinyl acetate copolymer, particularly an alkali component, thus resulting in lowering of the surface appearance or the deterioration of the mechanical strength such as impact strength.
An object of the present invention is to provide a thermoplastic resin composition excellent in the thermal stability.
Another object of the present invention is to provide a thermoplastic resin composition capable of giving molded articles having improved surface properties without impairing the processability and the mechanical strength existing in the thermoplastic resin itself.
The above and other objects of the present invention will become apparent from the description hereafter.